Current sensor

Abstract

A current sensor has a bus bar in which a current under measurement flows and also has a magnetic detection unit placed so as to face the bus bar, the magnetic detection unit sensing a magnetic field generated around the bus bar. The bus bar is formed from a laminate material in which a first metal material and a second metal material, which are different types of metal materials, are laminated. The first metal material has a larger density than the second metal material, and also has a smaller electrical resistivity than the second metal material. The magnetic detection unit is placed so as to face a surface of the bus bar, the surface being formed from the first metal material.

What is claimed is: 
     
         1 . A current sensor comprising:
 a bus bar in which a current under measurement flows; and   a magnetic detection unit placed so as to face the bus bar, the magnetic detection unit sensing a magnetic field generated around the bus bar; wherein   the bus bar is formed from a laminate material in which a first metal material and a second metal material, which are different types of metal materials, are laminated,   the first metal material has a larger density than the second metal material, and has a smaller electrical resistivity than the second metal material,   the magnetic detection unit is placed so as to face a surface of the bus bar, the surface being formed from the first metal material, and   in a lamination direction, the second metal material has a larger dimension than the first metal material.   
     
     
         2 . The current sensor according to  claim 1 , wherein in the lamination direction, the dimension of the second metal material is 80% or more of the dimension of the lamination material. 
     
     
         3 . A current sensor comprising:
 a bus bar in which a current under measurement flows; and   a magnetic detection unit placed so as to face the bus bar, the magnetic detection unit sensing a magnetic field generated around the bus bar; wherein   the bus bar is formed from a laminate material in which a first metal material and a second metal material, which are different types of metal materials, are laminated,   the first metal material has a larger density than the second metal material, and has a smaller electrical resistivity than the second metal material,   the magnetic detection unit is placed so as to face a surface of the bus bar, the surface being formed from the second metal material, and   in a lamination direction, the second metal material has a larger dimension than the first metal material.   
     
     
         4 . The current sensor according to  claim 3 , wherein in the lamination direction, the dimension of the second metal material is 60% or more of the dimension of the lamination material. 
     
     
         5 . A current sensor comprising a plurality of measurement phases, each of which is composed of a bus bar in which a current under measurement flows, and also has a magnetic detection unit placed so as to face the bus bar, the magnetic detection unit sensing a magnetic field generated around the bus bar, wherein:
 the bus bar is formed from a laminate material in which a first metal material and a second metal material, which are different types of metal materials, are laminated;   the first metal material has a larger density than the second metal material, and has a smaller electrical resistivity than the second metal material;   the plurality of measurement phases include a first measurement phase in which the magnetic detection unit is placed so as to face a surface of the bus bar, the surface being formed from the first metal material, and also include a second measurement phase in which the magnetic detection unit placed so as to face a surface of the bus bar, the surface being formed from the second metal material; and   at least one of item I and item II below is satisfied
 item I: in a lamination direction, the second metal material has a larger dimension than the first metal material, and 
 item II: in at least one measurement phase, the bus bar has a bent portion, and the magnetic detection unit is placed at a position at which the magnetic detection unit is capable of sensing induced magnetic fields from two portions positioned with the bent portion interposed between the two portions in the bus bar. 
   
     
     
         6 . The current sensor according to  claim 5 , wherein second measurement phases are adjacently placed on both sides of the first measurement phase. 
     
     
         7 . The current sensor according to  claim 5 , wherein:
 item II above is satisfied;   in the bus bar, the first metal material is provided on a side on which the bent portion is bent; and   the magnetic detection unit faces a layer of the first metal material of the bus bar.   
     
     
         8 . The current sensor according to  claim 1 , wherein:
 the first metal material is a copper material; and   the second metal material is an aluminum material.